Rosemary Zaleski, ExxonMobil Biomedical Sciences, Inc., and

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Time Use Research for Exposure and Risk Assessment

• Rosemary Zaleski, ExxonMobil Biomedical
  Sciences, Inc., and
• Virpi Tenhola, KTL National Public Health
  Institute, Finland
• International Association for Time Use Reseach
• Brussels, Belgium, September 2003

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Introduction

• Ultimate Goal Ensuring protection of public
  health
• Risk function of (hazard, exposure)
• Exposure data critical to estimate risk
• Develop most realistic, complete estimates of
  exposure as possible
• Time Use Information is critical to developing
  exposure estimates

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Time Use Information and Exposure Assessment

• Exposure
• Media Concentration X Intake Rate X Contact
  Time
• e.g., Inhalation Exposure (mg/day)
• Pollutant in air (mg/m3) X Breathing Rate
  (m3/hr) X Time (hrs/day)
• Occupational scenario requires time at work in
  task area
• Indoor residential scenario requires time
  indoors at home
• age-specific exposures require age-specific time
  indoors
• multi-chamber residence models require
  room-specific movement patterns

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Example of Exposure Model Input Data
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Examples of Time Use Parameters Relevant for
Exposure Assessment

• Hours indoors/outdoors
• Time in specific environments (home, work,
  school, driving)
• Time in specific microenvironments (kitchen,
  bedroom, garage)
• Time in specific tasks (gardening, recreation,
  bathing)
• Time using or in presence of certain products
  (paints, adhesives, cigarettes)
• Residence time, employment tenure

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Ideal Level of Information for Time Use
Parameters for Exposure Assessment

• Distributions
• by age
• by gender
• by time of year
• by region or population
• by activity level
• by other significant factors
• significant factors may differ across time
  parameters
• ex. Day of week, employment status, education
  status
• Sequentially (preserve potential correlations)

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Why Does Time Use Information Matter?

• A few of the many applications of time use
  information in exposure and risk assessment
  include
• Occupational exposure and safety assessment
• Consumer product safety assessment
• Childrens exposure assessment
• Ambient air pollutant risk assessment
• Environmental emissions exposure and risk
  assessment

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Examples of Time Use Data in Exposure Assessment

• US National Human Activity Pattern Survey
• distributional data by environments (e.g., work)
  and activities (e.g., bathing)
• Summary data in USEPA Exposure Factors Handbook
  http//cfpub.epa.gov/ncea/cfm/recordisplay.cfm?dei
  d12464
• US Consolidated Human Activity Database
• includes activity level estimates for each task
• http//www.epa.gov/chadnet1/

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Examples of Time Use Data in Exposure Assessment
(contd)

• ECETOC European Exposure Factors Sourcebook, with
  Focus on UK Data
• OECD years with employer for multiple countries
• Gershuny 1995 estimated weekly work hours for
  multiple countries

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Multinational Time Use Data Relevance for
Exposure Estimates
Differences weekly work hours employer tenure
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Summary So Far

• Time use data for exposure assessment is nowadays
  mostly from the U.S.
• For other countries, data are still (largely)
  missing
• Always looking for most current, representative
  data
• Possible ways to leverage social science and
  exposure science studies
• EPA/ ACC RfA announcement http//es.epa.gov/ncer/
  rfa/current/2003_enviro_stat.htm
• ExpoFacts http//www.ktl.fi/expofacts/

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ExpoFacts
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ExpoFacts

• The database will be free to use
• The database will be available on the Internet
• Users can search and combine data tables to best
  suit their needs
• The database will be published in 2004
• Do you have data for ExpoFacts?
• Do you want to use the ExpoFacts?

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Conclusions

• Ultimate Goal Ensuring protection of public
  health
• Risk fn (hazard, exposure)
• Exposure data critical to estimate risk
• Develop most realistic, complete estimates of
  exposure as possible
• Time Use Information
• Critical to developing exposure estimates
• Utilize all sources of relevant data
• Interdisciplinary studies - a good use of time!